1. Field of the Invention
This invention pertains to apparatus and method for supplying an intra-ocular lens (IOL) to an eye, which may be an accommodating lens, and providing other benefits in treatment of the natural lens of an eye. More particularly, a structure adapted to be placed in a human lens capsule along with one or two lens optics is supplied, along with methods of using.
2. Description of Related Art
A young human eye has a natural “accommodation” ability, which is the ability to focus on both near and far objects. Contraction and relaxation of the ciliary muscle provides the eye with this ability. Ciliary muscle action shapes the natural crystalline lens in the eye to the appropriate optical configuration for focusing light rays entering the eye on the retina. Because of physiological changes with age, the human eye often loses this natural accommodation ability and develops a condition called “presbyopia.” Furthermore, the natural crystalline lens often develops a cataract, which is an opaque region of the lens. This condition leads to widespread application of techniques to remove the natural crystalline lens. Often a conventional intra-ocular lens (IOL) is then placed in the eye. The conventional (monofocal) IOL has very limited, if any, accommodating ability. The wearer or user of the conventional IOL then may use corrective spectacles as a useful aid in vision. Multi-focal IOL's without accommodating movement have been used to provide near and far vision correction.
A variety of attempts have been made to provide IOL's with accommodating movement in the eye. One such device is the CRYSTALENS, which was approved for use in the United States in November, 2003. (Another accommodating lens has been approved for use in Europe.) The CRYSTALENS has a single optic attached to hinged haptics. The optic is vaulted in the posterior position against the posterior capsule. Operation of the ciliary muscle increases the pressure in the vitreous humor, moving the optic in an anterior direction, thereby increasing the power of the optic. Relaxation of the ciliary muscle allows the lens to move backward. The forward and backward motion simulates natural lens accommodation. The amount of accommodation is limited, however. The CRYSTALENS normally includes a relatively small optic zone to enhance optic movement, but thereby this increases the chances of nighttime glare and halos.
Another approach to obtaining accommodation is disclosed in U.S. Pat. No. 6,645,246 B1. An accommodating IOL employs an optic made of two different materials to enhance the accommodation achievable in the eye in response to normal accommodative stimuli. The optic includes a first lens portion surrounding a second lens portion that is less deformable than the first portion. The optic can be sized and configured to fit within the capsular bag.
Researchers have envisioned a soft, elastic polymer gel that may someday be used to replace the clouded natural lens that is removed during cataract surgery. This approach is considered by some researchers also as a possible mechanism to correct presbyopia. The gel would be injected into the capsular bag after the eye's natural lens is removed. The material may be a modified hydrogel, similar to that used for extended wear contact lenses. Its injectability could eliminate the need for the larger incision that is normally required to insert a replacement IOL. One of the limitations of this approach is that the gel must have a high refractive index. Also, a method for re-sealing the lens capsule will be required.
When IOLs are placed in the capsule of an eye, tissue growth around the haptics or other position fixation apparatus occurs, particularly when the lens has been implanted for an extended period of time. Also, adhesion of tissue to the lens or its haptics occurs. This, in most cases, eliminates the possibility of removing or adjusting an existing implanted lens and replacing it with a more efficacious optic. Also, when greater accommodation is needed using accommodating IOLs, keeping the lens capsule open would be beneficial. Pressure change in the vitreous humor because of muscle contraction will have greater effect on movement of an accommodating lens apparatus if volume of the capsule is maintained at a higher value. Holding the lens capsule open will also prevent the fusion of the anterior and posterior capsules and allow greater ease of accommodation and flexibility of the complex. Apparatus and method that would allow these further procedures in a pseudophakic eye are needed.
Surgical procedures to form an opening (capsulorhexis) in both the anterior capsule and the posterior capsule are sometimes necessary. Particularly in the eyes of younger patients, the capsule opening is closed by growth of tissue in a relatively short time. Particularly in pediatric ophthalmology, there is a need for surgical apparatus and method to avoid the rapid closure of such openings. In adults, pseudoexfoliation syndrome is also complicated by contraction of the capsule (phimosis) with resultant visual disturbance and damage to supporting zonules.
Contraction of the anterior capsule also occurs in eyes where the CRYSTALENS has been implanted. The capsular contraction can cause posterior displacement of the CRYSTALENS, resulting in hyperopia, or extreme contraction of the capsule results in asymmetric compression of the CRYSTALENS with significant power changes including myopia and astigmatism, e.g., “Z Compression.”
What is needed is apparatus and method for providing accommodating lenses that allow greater range of accommodation, allowing a user to obtain near and distant vision without eyeglasses. When openings are surgically formed in the capsule to implant IOLs or perform other surgical procedures, there is a need to provide apparatus and procedure to maintain the form of the lens capsule and to maintain the diameter of a capsulotomy opening.